Field of the Invention
This invention relates to tube couplings and particularly, though not exclusively applicable to couplings for metal tubing such as in fuel or brake fluid lines as used in motor vehicles.
U.K. Patent Publication No. 1,520,742 discloses a tube coupling comprising a body having a throughway open at one end to receive a tube, the throughway having a tapered cam surface extending towards said one end and a collet comprising an annular sleeve located in the open end of the throughway and having resilient arms projecting axially into the throughway. The resilient arms of the collet engage the tapered cam surface with movement of the collet outwardly of the throughway to grip and lock the tube in place. The tube is released from the collet by depressing the collet into the throughway.
U.K. Patent Publication No. 1,573,757 discloses a tube coupling of the form described and illustrated in U.K. Patent Specification No. 1,520,742 in which the resilient extending arms of the collet have outer faces shaped to which bear against the tapered cam surface adjacent the sleeve portion of the collet. The inner sides of the arms have inwardly facing projections spaced towards the free ends of the arms to produce positive engagement with the tube.
U.K. Patent Publication No. 2,132,296 discloses a tube coupling of the form described and illustrated in U.K. Patent Publication Nos. 1,520,742 and 1,573,757 in which the coupling body is provided with an end cover, having a base wall formed with an aperture through which a tube can extend into the coupling body and a peripheral wall to engage around the outer periphery of the coupling body. An attachment arrangement is provided between the peripheral wall of the end cover and coupling body which enables the cover to be removed when it is required to release the tube from the coupling body but which prevents the base wall of the cover being accidentally pressed into engagement with the projecting end of the collet from the coupling body which could inadvertantly release the tube from the coupling body.
European Patent Publication No. 0,255,368 discloses a tube coupling in which the end cover has manually operable members for engaging the projecting end of the collet to depress the collet into the throughway and thereby release the tube gripped in the coupling body.
European Patent Publication No 0280180 relates to a coupling bushing for connecting the ends of free lines for fluid media, in particular for fuel lines on internal combustion engines, having a bushing part which has at least one insertion opening, provided with an elastic sealing element, for receiving a line end provided with a holding shoulder, and having a blocking member engaging behind the holding shoulder of the line end. This arrangement is however difficult to operate and in particular is difficult to release when required.
This invention provides a tube coupling comprising a coupling body having a throughway open at one end to receive a tube means in the throughway to grip the tube and resist extraction of the tube from the throughway, detent means located on the coupling body to act on an annular abutment on the tube to retain the tube in the coupling body and one release means for releasing both the detent means and tube gripping means to allow release of the tube from the coupling.
Preferably the tube gripping means has means to relieve the gripping action projecting from the open end of the throughway and operable by being depressed into the throughway and the release means serves to release said detent means and to depress the tube gripping means for release of a tube.
It is also preferred that the coupling body has an enclosure for the open end of the coupling body having an aperture through which a tube to be inserted into the throughway may extend, the detent means for engaging the further annular abutment on the tube being located in the enclosure and said release means being provided on the enclosure for releasing both the detent means and tube gripping means.
In one construction according to the invention the detent means may comprise a collet which is located in the enclosure for limited axial movement between an end wall of the enclosure and the end of the coupling body, the collet having an annular head engageable with said grip relieving means projecting from the coupling body and radially resilient fingers projecting towards the end wall of the enclosure which snap over an abutment on a tube inserted into the coupling body to assist in retaining the tube in the coupling body.
More specifically the end wall of the enclosure may have an inwardly facing abutment surface with which the ends of the fingers are engagable to hold the fingers against radial outward movement thereby locking tube in a direction outwardly of the coupling body drawing the grip relieving means outwardly of the body until the gripping means act and the resulting movement of the collet with the grip relieving means engaging the collet fingers with the abutment surface.
For example the release means on the enclosure may comprise means to displace the collet into engagement with the grip relieving means to extract the ends of the fingers from the abutment surface on the enclosure and to displace the grip relieving means inwardly into the tube coupling body to allow a tube to be extracted from the coupling body.
In particular the abutment surface in the enclosure may extend around the aperture in the enclosure for the tube.
The annular head of the collet may be formed with an encircling angled ramp face on the side disposed away from the coupling body and depressable plunger elements may be mounted on the enclosure having angled cam faces engagable with the ramp face on the collet to space the collet towards the coupling body with depression of the plungers.
By way of example the depressable plungers may be formed integrally with flexible webs formed in the wall of the enclosure.
In any of the above arrangements said tube gripping means/grip relieving means may comprise a collet having a head disposed outside the coupling body and a plurality of resilient fingers projecting into the coupling body and the throughway may have an internal cam surface which tapers towards the open end of the throughway with which the fingers are engageable to be depressed radially inwardly to engage and grip a tube with movement of the collet outwardly of the throughway and to release the grip with inward movement.
In particular an annular cam element may be mounted in the throughway of the coupling body facing towards the collet with which the ends of the resilient fingers of the collet are engagable when the collet is depressed into the throughway to expand the fingers and thereby release their engagement from the tube.
In an alternative arrangement the tube gripping/relieving means may comprise a grab ring mounted in the throughway and a sleeve extending from the grab ring from the open end of the throughway depressing of which relieves the grip of the grab ring.
The invention also provides a coupling body having a throughway open at one end to receive a tube, an enclosure on the body extending over said end with an end wall of the enclosure spaced from the end of the coupling body and having an aperture to receive the tube, a collet mounted in the enclosure for limited axial movement between the end wall and the coupling body, the collet having a head adjacent the coupling body and resilient fingers projecting towards the end wall of the enclosure to snap over an annular abutment on the tube inserted through the enclosure into the coupling body and release means on the enclosure to release the fingers from the abutment to allow extraction of the tube.
In accordance with a further feature of the invention, the resilient fingers of the collet may taper towards the head of the collet to increase the radial flexibility of the fingers adjacent the collet head.
More specifically, the collet may have three resilient fingers, the free ends of which are closely spaced and which taper in width towards the head of the collet.
In accordance with a still further feature of the invention, the collet may be aligned with the throughway in the coupling body by means of an intermediate sleeve extending between the throughway and collet.
More specifically, the sleeve may extend into the head end of the collet and may be provided with an encircling shoulder which is seated in a counter bore at the end of the collet.
In any of the above arrangements one or more O-ring seals may be mounted in the throughway in the coupling body to seal the external surface of the tube inserted in the coupling body.